In order to achieve a substantially lighter weight bus-type vehicle, applicant utilizes a generally monocoque type body construction wherein the bus body components are integrated in such a way as to distribute loads throughout the body construction as opposed to earlier designs where a heavy duty frame or chassis is the main load carrying portion of a vehicle. Applicant's vehicle construction is generally modular in nature. In the present vehicle design the longitudinally frontmost module of the body projects forwardly of the steerable front wheels and contains the front door, the driver's seat or position and, in certain cases, an extendible passenger loading ramp such as shown in applicant's U.S. Pat. No. 4,131,209.
There are generally two operating conditions under which the forwardly projecting body module can be damaged and, at least in one case, cause damage to the front suspension which supports the steerable wheels. The present invention includes an energy absorbing brace system which coacts with the vehicle underbody in a way to transmit and/or absorb bumper induced loads so as to minimize damage to the vehicle body and front suspension.
A first mode in which damage can occur to a vehicle having a projecting front end is when the vehicle is being towed. Frequently, the vehicle bumper is secured directly to the vehicle body in such a way as to transmit the towing loads directly through the relatively lightweight body structure. In such cases the towing loads, in many instances, have been sufficiently high as to either severely distort or to completely sever the projecting front module from the remainder of the vehicle. Another source of vehicle damage can occur during a front end collision wherein the overhanging or projecting front end module collapses sufficiently to damage the front suspension which supports the steerable wheels. In the present invention, applicant has developed a bracing arrangement associated with the forwardly projecting module which supports the front bumper in a way as to transmit towing loads to the vehicle underbody and the front suspension in a way as to prevent damage to the vehicle body and, at the same time, absorbs the energy of a front end collision in such a way as to minimize damage to the vehicle body and front suspension.
More specifically, the bumper support and suspension system of the present invention includes an underbody extending substantially throughout the length and width of said main body and includes a first transverse beam or support member disposed forwardly of the driver position and front door, a second transverse beam disposed immediately rearwardly of the driver position and a third transverse beam spaced rearwardly of said second beam. The transverse beams or members longitudinally define the aforementioned modules. The system also includes a steerable wheel-supporting subframe articulated at its longitudinally forward end to the second transverse beam and having a longitudinally rear portion which is disposed proximate the third transverse beam. Spring means are disposed between the rear portion of the subframe and the third transverse beam to permit the underbody to move vertically relative to the subframe. The system also includes a pair of energy absorbing and transmitting brace elements the respective rear ends of which are fixed to the transverse mid-portion of the second transverse beam. The brace elements forwardly diverge transversely outwardly relative to their respective rear ends and are attached to the first transverse beam or support member. The forward ends of the brace elements project longitudinally beyond the first transverse beam and are adapted to support thereon a front bumper member.
Thus, during towing the towing loads are transmitted through the brace elements to that portion of the underbody to which the front suspension or subframe is secured whereby the towing loads are carried by the underbody and subframe. In the case of a front end collision, the diverging brace elements will deflect or bow outwardly to absorb a portion of the energy of the collision impact and a portion of which load will also be absorbed by the transverse underbody beam to which the subframe is articulated.
Articulated subframes supporting steerable wheels are shown in the following U.S. patents: U.S. Pat. No. 1,479,187 Lansden; U.S. Pat. No. 3,768,825 Magnusson; and U.S. Pat. No. 4,248,455 Manning. None of these references discloses the use of energy absorbing and transmitting brace elements disposed forwardly of the articulated subframes. Thus, in the case of Lansden and Magnusson a front end collision would transmit the impact thereof directly to the wheel supporting subframe causing the latter to be damaged. In the case of Manning, towing loads would be carried by the overhanging or projecting forward portion of the vehicle thereby subjecting the latter to distortion or other possible damage. Without such energy absorbing brace elements forward of the front end suspension, the prior art systems cannot prevent damage to the vehicle body or front suspension under towing and front end collision conditions.
Various other advantages are achieved with applicant's invention which is shown in the drawings and hereinafter described in detail.